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41.
Thilo C. Fischer Christian Gosch Judith Pfeiffer Heidrun Halbwirth Christian Halle Karl Stich Gert Forkmann 《Trees - Structure and Function》2007,21(5):521-529
Pear (Pyrus sp.) is a major fruit crop of temperate regions with increasing extent of cultivation. Pear flavonoids contribute to its fruit
color, pathogen defense, and are health beneficial ingredients of the fruits. Comparative Southern analyses with apple (Malus x domestica) cDNAs showed comparable genomic organization of flavonoid genes of both related genera. A homology-based cloning approach
was used to obtain the cDNAs of most enzymes of the main flavonoid pathway of Pyrus: phenylalanine ammonia lyase, chalcone synthase, chalcone isomerase, flavanone 3β-hydroxylase, flavonol synthase, dihydroflavonol
4-reductase, leucoanthocyanidin reductase 1 and 2, anthocyanidin synthase, anthocyanidin reductase, and UDP-glucose : flavonoid
7-O-glucosyltransferase. The substrate specificities of the recombinant enzymes expressed in yeast were determined for physiological
and non-physiological substrates and found to be in general agreement with the characteristic pear flavonoid metabolite pattern
of mainly B-ring dihydroxylated anthocyanins, flavonols, catechins, and flavanones. Furthermore, significant differences in
substrate specificities and gene copy numbers in comparison to Malus were identified. Cloning of the cDNAs and studying the enzymes of the Pyrus flavonoid pathway is an essential task toward a comprehensive knowledge of Pyrus polyphenol metabolism. It also elucidates evolutionary patterns of flavonoid/polyphenol pathways in the Rosaceae, which allocate
several important crop plants. 相似文献
42.
Pawlowski K Jacobsen KR Alloisio N Ford Denison R Klein M Tjepkema JD Winzer T Sirrenberg A Guan C Berry AM 《Plant biology (Stuttgart, Germany)》2007,9(6):776-785
Three types of hemoglobins exist in higher plants, symbiotic, non-symbiotic, and truncated hemoglobins. Symbiotic (class II) hemoglobins play a role in oxygen supply to intracellular nitrogen-fixing symbionts in legume root nodules, and in one case ( Parasponia Sp.), a non-symbiotic (class I) hemoglobin has been recruited for this function. Here we report the induction of a host gene, dgtrHB1, encoding a truncated hemoglobin in Frankia-induced nodules of the actinorhizal plant Datisca glomerata. Induction takes place specifically in cells infected by the microsymbiont, prior to the onset of bacterial nitrogen fixation. A bacterial gene (Frankia trHBO) encoding a truncated hemoglobin with O (2)-binding kinetics suitable for the facilitation of O (2) diffusion ( ) is also expressed in symbiosis. Nodule oximetry confirms the presence of a molecule that binds oxygen reversibly in D. glomerata nodules, but indicates a low overall hemoglobin concentration suggesting a local function. Frankia trHbO is likely to be responsible for this activity. The function of the D. glomerata truncated hemoglobin is unknown; a possible role in nitric oxide detoxification is suggested. 相似文献
43.
Sabine Favre-Bonté Eric Chamot Thilo Köhler Jacques-A Romand Christian van Delden 《BMC microbiology》2007,7(1):33
Background
Pseudomonas aeruginosa frequently colonizes and is responsible for severe ventilator-associated pneumonia in intubated patients. A quorum-sensing (QS) circuit, depending on the production of the two QS-signaling molecules (autoinducers, AIs) 3-oxo-C12-HSL and C4-HSL, regulates the production by P. aeruginosa of several virulence factors and is required for biofilm formation. Therefore QS-inhibition has been suggested as a new target for preventive and/or therapeutic strategies. However the precise role of QS during colonization and subsequent infections of intubated patients remains unclear. 相似文献44.
Al-Masoudi NA Al-Soud YA Ali IA Schuppler T Pannecouque C De Clercq E 《Nucleosides, nucleotides & nucleic acids》2007,26(3):223-230
New derivatives of azidothymidine (AZT) substituted by alkyl and alkylsulphonyl groups at N-3 and C-5', respectively, have been synthesized. The new synthesized derivatives showed remarkable anti-HIV-1 and HIV-2 activity in MT-4 cells. Compounds 8 and 10 have IC(50) values of 0.83 and 0.31 microg/mL against HIV-1 with therapeutic index of 83 and 403, respectively, and IC(50) values of 0.93 and 0.29 microg/mL against HIV-2 with therapeutic index of 74 and 431, respectively. This means that compounds 8 and 10 were cytotoxic to MT-4 cells at CC(50) of 69.2 microg/mL and 125 microg/mL, respectively. 相似文献
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48.
Drivers of temporal changes in temperate forest plant diversity vary across spatial scales
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Markus Bernhardt‐Römermann Lander Baeten Dylan Craven Pieter De Frenne Radim Hédl Jonathan Lenoir Didier Bert Jörg Brunet Markéta Chudomelová Guillaume Decocq Hartmut Dierschke Thomas Dirnböck Inken Dörfler Thilo Heinken Martin Hermy Patrick Hommel Bogdan Jaroszewicz Andrzej Keczyński Daniel L. Kelly Keith J. Kirby Martin Kopecký Martin Macek František Máliš Michael Mirtl Fraser J.G. Mitchell Tobias Naaf Miles Newman George Peterken Petr Petřík Wolfgang Schmidt Tibor Standovár Zoltán Tóth Hans Van Calster Gorik Verstraeten Jozef Vladovič Ondřej Vild Monika Wulf Kris Verheyen 《Global Change Biology》2015,21(10):3726-3737
Global biodiversity is affected by numerous environmental drivers. Yet, the extent to which global environmental changes contribute to changes in local diversity is poorly understood. We investigated biodiversity changes in a meta‐analysis of 39 resurvey studies in European temperate forests (3988 vegetation records in total, 17–75 years between the two surveys) by assessing the importance of (i) coarse‐resolution (i.e., among sites) vs. fine‐resolution (i.e., within sites) environmental differences and (ii) changing environmental conditions between surveys. Our results clarify the mechanisms underlying the direction and magnitude of local‐scale biodiversity changes. While not detecting any net local diversity loss, we observed considerable among‐site variation, partly explained by temporal changes in light availability (a local driver) and density of large herbivores (a regional driver). Furthermore, strong evidence was found that presurvey levels of nitrogen deposition determined subsequent diversity changes. We conclude that models forecasting future biodiversity changes should consider coarse‐resolution environmental changes, account for differences in baseline environmental conditions and for local changes in fine‐resolution environmental conditions. 相似文献
49.
Neutrophil activation by Candida glabrata but not Candida albicans promotes fungal uptake by monocytes
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Seána Duggan Fabian Essig Kerstin Hünniger Zeinab Mokhtari Laura Bauer Teresa Lehnert Susanne Brandes Antje Häder Ilse D. Jacobsen Ronny Martin Marc Thilo Figge Oliver Kurzai 《Cellular microbiology》2015,17(9):1259-1276
Candida albicans and Candida glabrata account for the majority of candidiasis cases worldwide. Although both species are in the same genus, they differ in key virulence attributes. Within this work, live cell imaging was used to examine the dynamics of neutrophil activation after confrontation with either C. albicans or C. glabrata. Analyses revealed higher phagocytosis rates of C. albicans than C. glabrata that resulted in stronger PMN (polymorphonuclear cells) activation by C. albicans. Furthermore, we observed differences in the secretion of chemokines, indicating chemotactic differences in PMN signalling towards recruitment of further immune cells upon confrontation with Candida spp. Supernatants from co‐incubations of neutrophils with C. glabrata primarily attracted monocytes and increased the phagocytosis of C. glabrata by monocytes. In contrast, PMN activation by C. albicans resulted in recruitment of more neutrophils. Two complex infection models confirmed distinct targeting of immune cell populations by the two Candida spp.: In a human whole blood infection model, C. glabrata was more effectively taken up by monocytes than C. albicans and histopathological analyses of murine model infections confirmed primarily monocytic infiltrates in C. glabrata kidney infection in contrast to PMN‐dominated infiltrates in C. albicans infection. Taken together, our data demonstrate that the human opportunistic fungi C. albicans and C. glabrata are differentially recognized by neutrophils and one outcome of this differential recognition is the preferential uptake of C. glabrata by monocytes. 相似文献
50.
The GD1a glycan is a cellular receptor for adenoviruses causing epidemic keratoconjunctivitis 总被引:2,自引:0,他引:2
Nilsson EC Storm RJ Bauer J Johansson SM Lookene A Ångström J Hedenström M Eriksson TL Frängsmyr L Rinaldi S Willison HJ Pedrosa Domellöf F Stehle T Arnberg N 《Nature medicine》2011,17(1):105-109
Adenovirus type 37 (Ad37) is a leading cause of epidemic keratoconjunctivitis (EKC), a severe and highly contagious ocular disease. Whereas most other adenoviruses infect cells by engaging CD46 or the coxsackie and adenovirus receptor (CAR), Ad37 binds previously unknown sialic acid-containing cell surface molecules. By glycan array screening, we show here that the receptor-recognizing knob domain of the Ad37 fiber protein specifically binds a branched hexasaccharide that is present in the GD1a ganglioside and that features two terminal sialic acids. Soluble GD1a glycan and GD1a-binding antibodies efficiently prevented Ad37 virions from binding and infecting corneal cells. Unexpectedly, the receptor is constituted by one or more glycoproteins containing the GD1a glycan motif rather than the ganglioside itself, as shown by binding, infection and flow cytometry experiments. Molecular modeling, nuclear magnetic resonance and X-ray crystallography reveal that the two terminal sialic acids dock into two of three previously established sialic acid-binding sites in the trimeric Ad37 knob. Surface plasmon resonance analysis shows that the knob-GD1a glycan interaction has high affinity. Our findings therefore form a basis for the design and development of sialic acid-containing antiviral drugs for topical treatment of EKC. 相似文献